The present invention relates to exercise methods and apparatus and more particularly, to relatively compact exercise equipment which facilitates relatively favorable elliptical exercise motion.
Exercise equipment has been designed to facilitate a variety of exercise motions. For example, treadmills allow a person to walk or run in place; stepper machines allow a person to climb in place; bicycle machines allow a person to pedal in place; and other machines allow a person to skate and/or stride in place. Yet another type of exercise equipment has been designed to facilitate relatively more complicated exercise motions and/or to better simulate real life activity. Such equipment typically converts a relatively simple motion, such as circular, into a relatively more complex motion, such as elliptical.
U.S. Pat. No. 4,185,622 to Swenson discloses an exercise machine that generates elliptical exercise motion. Left and right foot supporting links have rearward ends which are rotatably coupled to respective cranks, and forward ends which are rotatably coupled to respective rocker links or guides. As a result, the rearward ends of the foot supporting links rotate in a circle together with the cranks; the forward ends of the foot supporting links move in reciprocal fashion together with the rocker links; and all intermediate points on the foot supporting links move through respective elliptical paths (which are similar in length but decrease in height as a function of distance from the crank axis). An advantage of this arrangement is that the heel of a user rises faster than his toe as the foot supporting link begins moving forward, and the heel of the user falls faster than the toe as the foot supporting link begins moving rearward.
U.S. Pat. No. 5,279,529 to Eschenbach also discloses an exercise machine that generates elliptical exercise motion. Left and right foot supporting links have rearward ends which are rotatably coupled to respective cranks, and forward ends which are rotatably coupled to respective rocker links on one embodiment (shown in FIG. 4 of the Eschenbach patent), and which are rotatably coupled to respective rollers on another embodiment (shown in FIG. 8 of the Eschenbach patent). As a result, the rearward ends of the foot supporting links rotate in a circle together with the cranks; the forward ends of the foot supporting links move in reciprocal fashion together with the rocker links or the rollers; and all intermediate points on the foot supporting links move through respective elliptical paths (which are similar in length but decrease in height as a function of distance from the crank axis). This arrangement similarly causes the heel of a user to rise faster than his toe as the foot supporting link begins moving forward, and the heel of the user to fall faster than the toe as the foot supporting link begins moving rearward.
Another feature of the machines shown in the Eschenbach patent is that the person""s feet may be selectively moved to different positions along the foot supporting links. As a result, all portions of the user""s feet may be positioned for movement through respective elliptical paths during rotation of the cranks. In other words, as compared to the Swenson machine, the person""s feet may be positioned for movement through somewhat flatter elliptical paths on the Eschenbach machines.
U.S. Pat. No. 5,242,343 to Miller also discloses an exercise machine that generates elliptical exercise motion. Left and right foot supporting links have rearward ends which are rotatably coupled to respective cranks, and forward ends which are rotatably coupled to respective rocker links on one embodiment (shown in FIG. 4 of the Miller patent), and which are rotatably coupled to respective rollers on another embodiment (shown in FIG. 1 of the Miller patent). As a result, the rearward ends of the foot supporting links rotate in a circle together with the cranks; the forward ends of the foot supporting links move in reciprocal fashion together with the rocker links or the rollers; and all intermediate points on the foot supporting links move through respective elliptical paths (which are similar in length but decrease in height as a function of distance from the crank axis). This arrangement similarly causes the heel of a user to rise faster than his toe as the foot supporting link begins moving forward, and the heel of the user to fall faster than the toe as the foot supporting link begins moving rearward.
Another feature of the machines shown in the Miller patent is that the foot supporting platforms occupy relatively forward positions along the foot supporting links. As a result, all portions of the user""s feet are positioned for movement through respective elliptical paths during rotation of the cranks. Moreover, as compared to the Eschenbach machine, the person""s feet are positioned for movement through somewhat flatter elliptical paths on the Miller machines. It is somewhat problematic to describe or compare the respective locations of and/or paths traveled by a person""s feet on the Miller machines and the Eschenbach machines because the analysis depends upon the size of a person""s feet. What can be said with certainty is that the Miller machines simulate a relatively flatter striding motion because the foot platforms are positioned to remain entirely forward of the crank diameter at all times.
As compared to the Swenson machine, the Miller machines use a relatively larger crank diameter to generate a longer stride. In order to generate a comfortable amount of rise in relation to the stride length, the foot platforms must be spaced a significant distance forward of the crank axis (to xe2x80x9cdilutexe2x80x9d the vertical component of the striding motion).
Generally speaking, a common shortcoming of many prior art machines (including those discussed above) is that a common linkage arrangement generates both the horizontal component of foot travel and the vertical component of foot travel. As a result, any desired increase in the length of foot motion necessarily involves an increase in the height of foot motion, as well. Unfortunately, this fixed aspect ratio is contrary to real life activity, since a person does not typically lift his legs higher and higher while taking strides which are longer and longer.
As a result of the direct relationship between horizontal foot travel and vertical foot travel, undesirable compromises were made to arrive at the prior art machines discussed above. For example, the Swenson machine is relatively compact, but the user""s heels travel through paths of motion which are nearly circular, and the user""s toes travel through paths of motion which are nearly arcuate. At the other extreme, the Miller machines guide all portions of the user""s feet through relatively flat elliptical paths of motion, but the machines are significantly longer than the Swenson machine. In fact, most prior art machines combine a relatively large crank diameter in order to generate a sufficiently long striding motion, and relatively long foot supports in order to reduce the associated vertical component of the striding motion (making the foot paths relatively flatter than they are long).
As suggested by the foregoing discussion, a need remains for a relatively compact elliptical motion exercise machine which generates a relatively long striding motion having a natural aspect ratio between stride length and stride height.
The present invention may be described in terms of linkage assemblies and corresponding exercise apparatus which link circular motion to relatively more complex, generally elliptical motion. More specifically, left and right cranks are rotatably mounted on a frame to provide rotating left and right connection points which define a crank diameter therebetween. Left and right foot supporting linkages are movably interconnected between the frame and respective connection points in such a manner that rotation of the cranks is linked to generally elliptical movement of left and right foot platforms. The linkages include foot supporting members which are connected, but not coupled, to respective connection points for purposes of determining vertical movement of a person""s feet (as a function of the crank diameter). The linkages also include drawbar arrangements which determine horizontal movement of the person""s feet (independent of the crank diameter). These xe2x80x9cdecoupledxe2x80x9d foot platforms or dual drive assemblies facilitate increases in stride length and/or decreases in machine length.
On a preferred embodiment, the foot supporting members are positioned adjacent one another and between opposite side cranks, thereby accommodating movement of a person""s feet between the cranks. This sort of arrangement allows for shorter machines without sacrificing stride length. At least one guard or shield may be provided between the foot platforms to eliminate pinch points and/or reduce the likelihood of the user""s feet or ankles striking one another during exercise.
In another respect, the present invention may be described in terms of linkage assemblies and corresponding exercise apparatus which link reciprocal motion to relatively more complex, generally elliptical motion. For example, left and right handlebar links may be rotatably connected to the frame and linked to at least one link in the elliptical motion linkage assembly. As the foot supports move through their generally elliptical paths, the handlebars pivot back and forth relative to the frame. In order to accommodate the proximity of the foot platforms on the preferred embodiment, the frame may be provided with opposite side posts for supporting respective handlebar links therebetween.
In yet another respect, the present invention may be described in terms of linkage assemblies and corresponding exercise apparatus which independently generate the horizontal and vertical components of generally elliptical exercise motion. In this regard, the foot platforms are driven up and down by respective cranks, and forward and backward by respective drawbar arrangements which have a range of motion in excess of the crank diameter defined between the crank connection points. The effect of the drawbar arrangements may be amplified by means of rocker links which support the foot supporting members at a first, relatively greater distance from the rocker axis, and which support the drawbars at a second, relatively smaller distance from the rocker axis. Additional features and/or advantages of the present invention may become apparent from the more detailed description that follows.